There are a variety of situations in which devices for detecting tampering are useful. This can include situations in which potentially hazardous or valuable substances or items, such as pharmaceuticals, chemicals, petrochemicals, etc., are stored in a container of some sort. This can also include situations in which it is desirable, for reasons of safety or security, to know whether certain items or locations have been accessed or tampered with. One particular field in which the detection of tampering is desirable is in air transportation. In order to ensure that aircraft are safe, significant time and effort may be spent in security sweeps of airplanes prior to flight. For airplane operators, the cost of these routine security sweeps is quite high, and performing such sweeps can keep airplanes grounded for significant periods.
One facet of security sweeps is to detect tampering with or access to restricted items or locations. To facilitate detection of such tampering, tamper-evident strips or seals are often used, such as shown in FIGS. 1A and 1B. As shown, this fairly traditional tamper-evident strip 10 is a butterfly-shaped adhesive sticker, having a central breakable region 12. The strip 10 is affixed with the breakable region 12 overlying or bridging an opening boundary 14 of a container 16 or other item to be secured. The adhesive of the strip 10 is chosen so that the strip 10 cannot be easily removed, and any attempts to remove it are revealed by tampered regions 18, which show evidence that the strip 10 has been peeled or picked-at. Likewise, opening of the container 16 will separate the opposing portions of the container across the opening boundary 14, breaking the strip 10 along the breakable region 12, so that after opening the container 16 the strip 10 will have a broken edge 20. When the strip seal is broken along the broken edge 20, this indicates that the area has been compromised.
Traditional tamper-evident strips rely almost entirely on the knowledge and thoroughness of the inspector, and can be overlooked in bad light, or be mistakenly overlooked when the seal or strip is broken. Traditional tamper-evident strips also rely on the knowledge of the inspector to know where to look. Consequently, the most common types of tamper-evident adhesive strips are usually made as visible as possible, such as with bright colors and bold lettering and/or logos, which may not be aesthetically desirable in many situations.
Other types of tamper-evident strips (not shown) have words, such as VOID or STOP, that are printed repeatedly on the strip, and appear only after the strip has been fully or partially peeled off or peeled open. These types of tamper-evident seals may be an improvement over some traditional strips, but still rely on the knowledge and thoroughness of an inspector to ensure confirmation. They also may be considered aesthetically undesirable by many users and observers.
The present application relates to one or more of the above issues.